<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>demo1</title>
</head>

<body>
  <canvas id="cvs"></canvas>
  <script>
    var canvas = document.getElementById('cvs');
    

  </script>
</body>

</html>